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xfs_fsr(8)                  System Manager's Manual                 xfs_fsr(8)

NAME
       xfs_fsr - filesystem reorganizer for XFS
SYNOPSIS
       xfs_fsr [-vdg] [-t seconds] [-p passes] [-f leftoff] [-m mtab]
       xfs_fsr [-vdg] [xfsdev | file] ...
       xfs_fsr -V
DESCRIPTION
       xfs_fsr is applicable only to XFS filesystems.
       xfs_fsr  improves the organization of mounted filesystems.  The reorga-
       nization algorithm operates on one file at a time, compacting or other-
       wise  improving  the  layout  of the file extents (contiguous blocks of
       file data).
       The following options are accepted by xfs_fsr.   The  -m,  -t,  and  -f
       options  have  no  meaning if any filesystems or files are specified on
       the command line.
       -m mtab      Use this file for the list of filesystems  to  reorganize.
                    The default is to use /etc/mtab.
       -t seconds   How  long  to  reorganize.  The default is 7200 seconds (2
                    hours).
       -p passes    Number of passes before terminating  global  re-org.   The
                    default is 10 passes.
       -f leftoff   Use  this  file  instead  of /var/tmp/.fsrlast to read the
                    state of where to start and as the file to store the state
                    of where reorganization left off.
       -v           Verbose.   Print cryptic information about each file being
                    reorganized.
       -d           Debug.  Print even more cryptic information.
       -g           Print to syslog (default if stdout not a tty).
       -V           Prints the version number and exits.

       When invoked with no arguments xfs_fsr reorganizes all regular files in
       all mounted filesystems.  xfs_fsr makes many cycles over /etc/mtab each
       time making a single pass over each XFS  filesystem.   Each  pass  goes
       through  and selects files that have the largest number of extents.  It
       attempts to defragment the top 10% of these files on each pass.
       It runs for up to two hours after which it records the filesystem where
       it  left off, so it can start there the next time.  This information is
       stored in the file /var/tmp/.fsrlast_xfs.   If  the  information  found
       here is somehow inconsistent or out of date it is ignored and reorgani-
       zation starts at  the  beginning  of  the  first  filesystem  found  in
       /etc/mtab.
       xfs_fsr  can  be  called  with one or more arguments naming filesystems
       (block device name), and files to reorganize.   In  this  mode  xfs_fsr
       does  not  read  or  write  /var/tmp/.fsrlast_xfs nor does it run for a
       fixed time interval.  It makes one pass through each specified  regular
       file  and  all  regular  files in each specified filesystem.  A command
       line name referring to  a  symbolic  link  (except  to  a  file  system
       device),  FIFO,  or UNIX domain socket generates a warning message, but
       is otherwise ignored.  While traversing the filesystem these  types  of
       files are silently skipped.
FILES
       /etc/mtab            contains  default  list  of filesystems to reorga-
                            nize.
       /var/tmp/.fsrlast_xfs
                            records the state where reorganization left off.
SEE ALSO
       xfs_fsr(8), mkfs.xfs(8), xfs_ncheck(8), xfs(5).
NOTES
       xfs_fsr improves the layout of extents for each  file  by  copying  the
       entire  file  to  a  temporary location and then interchanging the data
       extents of the target and temporary files in an  atomic  manner.   This
       method  requires  that  enough free disk space be available to copy any
       given file and that the space be  less  fragmented  than  the  original
       file.   It also requires the owner of the file to have enough remaining
       filespace quota to do the copy on systems running quotas.  xfs_fsr gen-
       erates a warning message if space is not sufficient to improve the tar-
       get file.
       A temporary file used in improving a file given on the command line  is
       created in the same parent directory of the target file and is prefixed
       by the string '.fsr'.  The temporary files used in improving an  entire
       XFS  device  are stored in a directory at the root of the target device
       and use the same naming scheme.  The temporary files are unlinked  upon
       creation so data will not be readable by any other process.
       xfs_fsr  does not operate on files that are currently mapped in memory.
       A 'file busy' error can be seen for these files  if  the  verbose  flag
       (-v) is set.
       Files marked as no-defrag will be skipped. The xfs_io(8) chattr command
       with the f attribute can be used to set or clear this flag.  Files  and
       directories created in a directory with the no-defrag flag will inherit
       the attribute.
       An entry in /etc/mtab or the file specified using the  -m  option  must
       have the rw option specified for read and write access.  If this option
       is not present, then xfs_fsr skips the  filesystem  described  by  that
       line.  See the fstab(5) reference page for more details.
       In  general  we do not foresee the need to run xfs_fsr on system parti-
       tions such as /, /boot and /usr as in general  these  will  not  suffer
       from  fragmentation.   There  are  also issues with defragmenting files
       lilo(8) uses to boot your system. It is recommended  that  these  files
       should  be  flagged  as  no-defrag  with  the xfs_io(8) chattr command.
       Should these files be moved by xfs_fsr then you must rerun lilo  before
       you reboot or you may have an unbootable system.

                                                                    xfs_fsr(8)